Inverted conical expandable retractor with coil spring

ABSTRACT

Access devices and related methods are disclosed that generally involve flexible or adjustable cannulas that have a substantially cylindrical insertion configuration and a substantially conical expanded configuration. Various methods and features are provided for transitioning the cannula from the insertion configuration to the expanded configuration while the access device is inserted through tissue to form a conical opening through the tissue. Examples include cables, biasing elements, retaining elements, bimodal rings, and coil springs. The devices and methods disclosed herein can allow for improved retention of the access device, improved angulation of instruments passed through the access device, and can increase the integrity of a seal formed between the access device and surrounding tissue.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is being filed concurrently with U.S.application Ser. No. ______ (Att. Docket No. 100873-386) entitled“INVERTED CONICAL EXPANDABLE RETRACTOR” which is incorporated byreference herein in its entirety.

FIELD OF THE INVENTION

The present invention relates to methods and devices for performingsurgical procedures, and in particular to methods and devices foraccessing a body cavity.

BACKGROUND OF THE INVENTION

In many surgical procedures, it is desirable to provide one or moreworking channels into a body cavity through which various instrumentscan be passed to view, engage, and/or treat tissue to achieve adiagnostic or therapeutic effect. In laparoscopic abdominal proceduresfor example, the abdominal cavity is generally insufflated with CO₂ gasto a pressure of around 15 mm Hg. The abdominal wall is pierced and oneor more tubular cannulas, each defining a working channel, are insertedinto the abdominal cavity. A laparoscopic telescope connected to anoperating room monitor can be used to visualize the operative field andcan be placed through one of the working channels. Other laparoscopicinstruments such as graspers, dissectors, scissors, retractors, etc. canalso be placed through one or more of the working channels to facilitatevarious manipulations by the surgeon and/or surgical assistant(s).

One problem with existing methods and devices is that these tubularcannulas limit the degree to which devices passed through the cannulacan be angulated with respect to the operative field. This canundesirably prolong and complicate the surgery, and in same cases canrequire placement of additional access devices and formation ofadditional incisions associated therewith.

Another drawback to existing access devices is that they can suffer frompoor retention and sealing capabilities. For example, angulation ofvarious surgical tools inserted through traditional cannulas cancompromise the seal between the cannula and the tissue wall, undesirablyallowing insufflation gas to escape. In addition, the cannula can have atendency to “back out” or slide proximally out of the incision.

Accordingly, there is a need for surgical access methods and devicesthat provide improved sealing, retention, and maneuverabilitycharacteristics.

SUMMARY OF THE INVENTION

The access devices and methods disclosed herein generally involveflexible or adjustable cannulas that have a substantially cylindricalinsertion configuration and a substantially conical expandedconfiguration. Various methods and features are provided fortransitioning the cannula from the insertion configuration to theexpanded configuration when the access device is inserted through tissueto form a conical opening through the tissue. Examples include cables,biasing elements, retaining elements, bimodal rings, and/or coilsprings. The devices and methods disclosed herein can allow for improvedretention of the access device, improved angulation of instrumentspassed through the access device, and can increase the integrity of aseal formed between the access device and surrounding tissue.

In one exemplary embodiment, an adjustable access device is provided.The access device can include a housing having a cannula extendingdistally therefrom. The housing and the cannula can define a workingchannel extending therethrough for receiving instruments and the accessdevice can include at least one seal element disposed within the workingchannel and configured to form a seal around an instrument disposedthrough the working channel and/or a seal across the working channelwhen no instrument is disposed therethrough. The cannula can have aninsertion configuration with a substantially constant outer diameterbetween a proximal end and a distal end, and an expanded configurationwherein the diameter increases from the proximal end of the cannula tothe distal end of the cannula. The cannula can be folded in the expandedconfiguration and unfolded in the insertion configuration.

In one embodiment, the cannula can include a flexible outer sheathhaving a plurality of folding walls disposed therein, each folding wallcomprising a plurality of segments. The plurality of segments caninclude a plurality of long segments separated from each other by atleast one short segment, and the segments can be defined by a pluralityof livings hinges formed in the folding walls. In one embodiment, theliving hinges alternate between being formed in an interior surface ofthe folding walls and being formed in an exterior surface of the foldingwalls. The plurality of long segments can have progressively increasinglengths from the proximal end of the folding walls to the distal end ofthe folding walls and each of the short segments can have lengths lessthan the long segments and substantially the same length as one another.

In another exemplary embodiment, the access device can include anactuator coupled between the housing and the cannula and configured tomove the cannula between the insertion configuration and the expandedconfiguration. For example, the actuator can comprise at least one cableextending distally from the housing to the distal end of the cannula.The housing can include a rotatable member coupled to the at least onecable and configured to rotate to selectively tension the at least onecable.

In another embodiment, the access device can include at least onebiasing element disposed within the cannula and configured to bias thecannula towards the expanded configuration. The access device can alsoinclude a horizontal retaining element coupled to the biasing elementsuch that the cannula is maintained in the insertion configurationand/or a vertical retaining element coupled to the biasing element suchthat the cannula is maintained in the expanded configuration.

In yet another exemplary embodiment, an adjustable access device isprovided that can include a cannula defining a working channel extendingtherethrough for receiving instruments, the cannula having an insertionconfiguration with a substantially constant outer diameter between aproximal end and a distal end, and an expanded configuration wherein theouter diameter increases from the proximal end of the cannula to thedistal end of the cannula. The access device can also include aplurality of springs disposed circumferentially around the cannula, thesprings being biased such that they apply an inward force to the cannulato bias the cannula to the expanded configuration. The cannula can beconfigured such that insertion of an obturator into the cannula iseffective to radially expand the plurality of springs to move thecannula to the insertion configuration and removal of the obturator fromthe working channel allows the springs to decrease in diameter to movethe cannula to the expanded configuration. The access device can alsoinclude an obturator insertable through the working channel of thecannula that is effective, when inserted, to radially expand theplurality of springs such that the cannula is shifted to the insertionconfiguration.

In one embodiment, the cannula can comprise a flexible outer sheathhaving a plurality of folding walls disposed therein, each folding wallcomprising a plurality of long segments separated from each other by atleast one short segment, wherein the segments are defined by a pluralityof living hinges formed in the folding walls.

In yet another embodiment, a method for accessing a surgical site isprovided that includes inserting a cannula through a tissue wall andfolding a plurality of folding walls of the cannula to form a conicalshaped opening through the tissue wall. Folding the plurality of foldingwalls can further include inserting an obturator through the cannula tosever at least one retaining element and allow at least one spring toexpand radially and/or applying tension to at least one cable coupled tothe distal end of the cannula. Folding the plurality of folding wallscan also include removing an obturator from the cannula to allow aplurality of springs to contract radially against an outer surface ofthe cannula.

In another embodiment, an adjustable access device is provided that caninclude a housing and an expandable cannula extending distally from thehousing, the expandable cannula including a coil spring having aproximal end coupled to the housing and a distal end configured torotate relative to the housing to adjust a diameter of the cannula suchthat the coil spring is effective to move the expandable cannula betweenan insertion configuration, in which the cannula has a substantiallyconstant outer diameter between a proximal end and a distal end, and anexpanded configuration, in which the diameter of the cannula increasesfrom the proximal end of the cannula to the distal end of the cannula.The access device can also include at least one seal element disposedwithin a working channel extending through the housing and the cannula,the at least one seal element being configured to form a seal around aninstrument disposed through the working channel and/or a seal across theworking channel when no instrument is disposed therethrough. The cannulacan include at least one sheath disposed around the coil spring and thedistal end of the coil spring can extend at least partially across alongitudinal axis of the cannula.

In one embodiment, the coil spring can have a plurality of coilsextending radially around a longitudinal axis of the cannula, the springbeing biased to an expanded configuration in which a distal coil of thespring has a diameter greater than a diameter of a proximal coil of thespring such that the spring defines a conical opening extendingtherethrough.

In another embodiment, the access device can include an obturator havinga distal end configured to engage the distal end of the coil spring suchthat rotation of the obturator is effective to rotate the distal end ofthe coil spring relative to the housing. The distal end of the obturatorcan include a longitudinally-extending slot formed therein for receivingand engaging the distal end of the coil spring. The obturator can alsoinclude a mating element formed on a proximal portion thereof, themating element being configured to engage the housing to preventrotation of the obturator with respect to the housing. In oneembodiment, the housing can include one or more suture anchors tofacilitate securing the housing to a tissue.

In yet another embodiment, a method for accessing a surgical site isprovided that includes inserting a cannula of a surgical access devicethrough a tissue wall and releasing a coil spring disposed within thecannula such that the coil spring radially expands to cause the cannulato radially expand into a conical configuration thereby forming aconical opening through the tissue wall. Releasing the coil spring caninclude releasing a distal end of the coil spring such that the distalend of the coil spring rotates relative to a proximal end of the coilspring and relative to a housing coupled to the proximal end of the coilspring. In one embodiment, the distal end of the coil spring can bereleased from an obturator engaging the coil spring. Releasing the coilspring can also include detaching an obturator from a housing coupled toa proximal end of the cannula to release a distal end of the coil springfrom a distal end of the obturator. In one embodiment, the method caninclude engaging a distal end of the coil spring and rotating the distalend of the coil spring relative to the housing to wind the coil springand thereby move the cannula to an insertion configuration, in which aninner diameter of the cannula is substantially constant.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be more fully understood from the following detaileddescription taken in conjunction with the accompanying drawings, inwhich:

FIG. 1 is a partially-exploded perspective view of one embodiment of anaccess device inserted in a tissue wall and having a cannula in aninsertion configuration;

FIG. 2 is a cross-sectional view of the access device and tissue wall ofFIG. 1, with the cannula shown in an expanded configuration;

FIG. 3 is a cross-sectional view of the access device of FIGS. 1-2 witha surgical tool inserted therethrough;

FIG. 4A is a perspective view of one embodiment of a seal housing;

FIG. 4B is a cross-sectional view of the seal housing of FIG. 4A,showing one embodiment of an instrument seal and a zero-closure seal;

FIG. 4C is an exploded perspective view of the instrument seal of FIG.4B;

FIG. 4D is a perspective view of the zero-closure seal of FIG. 4B;

FIG. 5A is a top view of a housing top portion of the access device ofFIGS. 1-2;

FIG. 5B is a cross-sectional side view of the housing top portion ofFIG. 5A;

FIG. 5C is a bottom view of the housing top portion of FIG. 5A;

FIG. 5D is a top view of a housing base portion of the access device ofFIGS. 1-2;

FIG. 5E is a cross-sectional side view of the housing base portion ofFIG. 5D;

FIG. 5F is a bottom view of the housing base portion of FIG. 5D;

FIG. 6A is a top view of the cannula of FIGS. 1-2;

FIG. 6B is a side view of the cannula of FIG. 6A;

FIG. 6C is a side view of a cannula folding wall of the cannula of FIGS.6A-6B in an unfolded position;

FIG. 6D is a side view of the cannula folding wall of FIG. 6C in afolded position;

FIG. 7A is a perspective view of another embodiment of an access deviceand an obturator configured to be inserted therethrough, the accessdevice having a cannula in an insertion configuration;

FIG. 7B is cross-sectional top view of one embodiment of a biasingelement, one embodiment of a retaining element, and the obturator ofFIG. 7A;

FIG. 7C is cross-sectional top view of one embodiment of a biasingelement having an expanded diameter larger than that of the biasingelement of FIG. 7B;

FIG. 7D is cross-sectional top view of one embodiment of a biasingelement having an expanded diameter larger than that of the biasingelement of FIG. 7C;

FIG. 7E is a cross-sectional side view of the access device of FIG. 7A,with the cannula shown in an expanded configuration;

FIG. 7F is a perspective view of an obturator and one embodiment of abiasing element having a horizontal retaining element and a verticalretaining element attached thereto;

FIG. 7G is a perspective view of the biasing element of FIG. 7F afterthe horizontal retaining element is severed;

FIG. 7H is a perspective view of the biasing element of FIGS. 7F and 7Gafter the vertical retaining element is severed;

FIG. 8A is a side view of one embodiment of bimodal ring and anobturator inserted partially therethrough;

FIG. 8B is a side view of the bimodal ring of FIG. 8A with the obturatorinserted fully therethrough;

FIG. 9A is a side view of another embodiment of an access device havinga cannula in an insertion configuration with an obturator insertedtherethrough;

FIG. 9B is a side view of the access device of FIG. 9A with theobturator removed to allow the cannula to move to an expandedconfiguration;

FIG. 10A is a cross-sectional side view of another embodiment of anaccess device having a coil spring disposed within a cannula and anobturator inserted therethrough, shown with the cannula in an insertionconfiguration;

FIG. 10B is a bottom view of the coil spring and obturator of FIG. 10A;

FIG. 10C is a cross-sectional view of the access device of FIG. 10A,with the obturator partially removed therefrom and the cannula in anexpanded configuration;

FIG. 10D is a cross-sectional view of the access device of FIG. 10A,with the obturator completely removed therefrom;

FIG. 10E is a cross-sectional view of a surgical tool inserted throughthe access device of FIG. 10A and angulated to a first position, with aphantom view of the surgical tool angulated to a second position; and

FIG. 10F is a cross-sectional view of the access device of FIG. 10A withthe obturator inserted to wind the coil spring.

DETAILED DESCRIPTION OF THE INVENTION

Certain exemplary embodiments will now be described to provide anoverall understanding of the principles of the structure, function,manufacture, and use of the devices and methods disclosed herein. One ormore examples of these embodiments are illustrated in the accompanyingdrawings. Those skilled in the art will understand that the devices andmethods specifically described herein and illustrated in theaccompanying drawings are non-limiting exemplary embodiments and thatthe scope of the present invention is defined solely by the claims. Thefeatures illustrated or described in connection with one exemplaryembodiment may be combined with the features of other embodiments. Suchmodifications and variations are intended to be included within thescope of the present invention.

A person skilled in the art will appreciate that, while methods anddevices are described herein in connection with minimally invasivelaparoscopic procedures in the abdominal cavity, the methods and devicescan be used in almost any part of a human or animal body and in variousother types of surgical procedures. By way of non-limiting example, thedevices and methods disclosed herein can be used in the thoracic cavity,pelvic cavity, cranial cavity and/or any of the body's natural orificesand can be used in endoscopic procedures and/or in open surgicalprocedures.

In general, surgical methods and access devices are provided thatinvolve flexible or adjustable cannulas that have a substantiallycylindrical insertion configuration and a substantially conical expandedconfiguration. Various features are provided for transitioning thecannula from the insertion configuration to the expanded configurationwhile it is inserted through tissue to form a conical opening throughthe tissue. Such devices and methods can allow for improved retention ofthe cannula, improved angulation of instruments passed through thecannula, and can increase the integrity of the seal between the cannulaand the tissue wall.

FIG. 1 illustrates one exemplary embodiment of an access device 10. Asshown, the access device 10 generally includes a housing 12 having acannula 14 extending distally therefrom. The cannula 14 can be insertedthrough a tissue wall 16 while the cannula is in a substantiallycylindrical insertion configuration with a substantially constant outerdiameter to access a body cavity 18. As shown in FIG. 2, the cannula 14can also have an expanded configuration in which the diameter of thecannula 14 increases from the proximal end 20 of the cannula to thedistal end 22. In an exemplary embodiment, the cannula 14 is unfolded inthe insertion configuration (FIG. 1) and is folded in the expandedconfiguration (FIG. 2). As discussed in detail below, an actuator can beprovided to facilitate folding and unfolding the cannula 14. Theactuator can have a variety of configurations, but in the illustratedembodiment, the actuator includes one or more cables 15. As shown inFIG. 3, the expanded cannula 14 can be effective to create a conicalopening 24 through the tissue wall 16. The conical opening 24 can allowa surgical instrument 26 inserted through the housing 12 and cannula 14to be angulated to a greater degree than traditional cylindricalopenings. In addition, the conical opening 24 can increase the integrityof the seal between the outer surface 27 of the cannula 14 and theincision surface 28 and can provide increased resistance to proximaltranslation of the access device 10 with respect to the tissue wall 16.

The access devices disclosed herein can include a seal housing that canbe formed integrally with the housing or can be selectively attachedthereto. A number of configurations are available for the seal housing.FIGS. 4A and 4B show one embodiment of a seal housing 30 having agenerally cylindrical shape. One or more openings 32 can be formed inthe proximal end of the seal housing 30 and the opening(s) can becoaxial or offset from an axis of a working channel 34 extending throughthe seal housing 30 and through the cannula 14. The seal housing 30 canalso include other features, such as an insufflation port 36 forallowing and preventing the passage of an insufflation fluid, e.g.carbon dioxide, through the access device 10 and into a body cavity.

Typically, during surgical procedures in a body cavity such as theabdomen, insufflation fluid is provided through the access device 10 toexpand the body cavity to facilitate the surgical procedure. In order tomaintain insufflation within the body cavity, the seal housing 30,housing 12, and/or cannula 14 can include at least one seal disposedtherein to prevent fluid from escaping. Various seal configurations areknown in the art, but typically the access device includes an instrumentseal that forms a seal around an instrument inserted therethrough, butotherwise does not form a seal when no instrument is insertedtherethrough, a trocar seal or zero-closure seal that seals the workingchannel when no instrument is inserted therethrough, or a combinationinstrument seal and trocar seal that is effective to both form a sealaround an instrument inserted therethrough and to form a seal in theworking channel when no instrument is inserted therethrough. In theembodiment shown in FIGS. 4A and 4B, the seal housing 30 includes aninstrument seal 40 and a separate trocar or zero-closure seal 42. Aperson skilled in the art will appreciate, however, that various otherseals known in the art can be used, including for example, flappervalves, gel seals, diaphragm seals, etc.

The instrument seal 40 is shown in more detail in FIG. 4C. As shown, theinstrument seal 40 is generally in the form of a multi-layer protectivemember 44 disposed on a proximal surface 46 of a multi-layer conicalseal 48. The multi-layer conical seal 48 can include a series ofoverlapping seal segments 50 that are assembled in a woven arrangementto provide a complete seal body. The seal segments 50 can be stacked ontop of one another or woven together in an overlapping fashion to formthe multi-layer seal 48 having a central opening 52 therein. The sealsegments 50 can be made from any number of materials known to thoseskilled in the art, but in an exemplary embodiment the seal segments 50are formed from an elastomeric material. The seal segments 50 can alsobe molded such that they have a varying thickness across the profile ofthe seal 48. Varying the thickness across the profile of the seal 48 canbe effective to minimize leakage and reduce drag forces on instrumentspassed therethrough. The multi-layer protective member 44 can similarlybe formed from a series of overlapping segments 54 that are disposedproximal to the overlapping seal segments 50 and that are configured toprotect the seal segments 50 from damage caused by surgical instrumentsinserted through the opening 52 in the seal 48. The protective member 44can also be formed from various materials, but in certain exemplaryembodiments the protective member 44 is formed from a moldedthermoplastic elastomer. The segments 50, 54 that form the seal 48 andthe protective member 44 can be held together using various techniquesknown in the art. As shown in FIG. 4C, the segments 50, 54 are heldtogether by several ring members that mate to engage the segments 50, 54therebetween. In particular, the protective member 44 is engaged betweena crown 56 and a gasket ring 58, and the seal 48 is engaged between thegasket ring 58 and a retainer ring 60. Pins 62 are used to mate the ringmembers 56, 58, 60 and to extend through and engage the segments of theseal 48 and the protective member 44.

When fully assembled, the instrument seal 40 can be disposed at variouslocations within the access device 10. In the embodiment illustrated inFIGS. 4A and 4B, the instrument seal 40 is disposed in the seal housing30 of the access device 10 at a location just distal of a proximalopening 32 and proximal of a trocar seal 42. Alternatively, or inaddition, one or more seals can be positioned in the housing 12 and/orthe cannula 14. In use, an instrument can be inserted into the center ofthe seal assembly and the seal segments 50, 54 can engage and form aseal around an outer surface of the instrument to thereby prevent thepassage of fluids through the seal 40. When no instrument is insertedtherethrough, the opening will not form a seal in the working channel34, however other configurations in which a seal is formed when noinstrument is inserted therethrough are also conceivable. Exemplaryinstrument seal configurations are described in more detail in U.S.Publication No. 2004/0230161 entitled “Trocar Seal Assembly,” filed onMar. 31, 2004, and U.S. Publication No. 2007/0185453 entitled “ConicalTrocar Seal,” filed on Oct. 15, 2003, which are hereby incorporated byreference in their entireties.

The trocar or zero-closure seal 42 in the illustrated embodiment isshown in more detail in FIG. 4D, and as shown, the illustratedzero-closure seal is in the form of a duckbill seal 64. The seal 64 isconfigured to form a seal in the working channel 34 when no instrumentis inserted therethrough to thus prevent the leakage of insufflationgases delivered through the access device 10 to the body cavity. Asshown, the duckbill seal 64 has a generally circular flange 66 with asidewall 68 extending distally therefrom. The shape of the sidewall 68can vary, but in the illustrated embodiment, the sidewall 68 isgenerally conical and extends in a distal direction to a seal face 72.The sidewall 68 is movable to allow the seal face 72 to move between aclosed position, in which no instrument is inserted therethrough and theseal face 72 seals the working channel 34 of the access device 10, andan open position in which an instrument is inserted therethrough. Theseal can include various other features, as described in more detail inU.S. Publication No. 2009/0005799 entitled “Duckbill Seal with FluidDrainage Feature,” filed on Jun. 29, 2007, which is hereby incorporatedby reference in its entirety. A variety of other duckbill-type seals areknown to those skilled in the art.

In accordance with the present disclosure the general structure of theseals as well as the seal housing do not generally form part of thepresent invention. As such, a person skilled in the art will appreciatethat various seal configurations, as well as various seal housings orother access devices, can be used without departing from the spirit ofthe invention disclosed herein.

The seal housing 30 can have a distal opening 74 defined by a distal rim76. The distal rim 76 can be configured to couple to a correspondingsnap ring 78 formed on a proximal surface of the housing 12. The sealhousing 30 can be formed integrally with the housing 12 or can becoupled thereto using a variety of means known in the art, including forexample friction fittings, a snap fittings, clamps, screws, pins,magnets, electromagnets, etc.

The housing 12 can have a variety of configurations. In the embodimentillustrated in FIGS. 1-3, the housing 12 is generally in the form of anannular disk. The housing has a distal base portion 80 and a proximaltop portion 82. The top portion 82 is shown in more detail in FIGS.5A-5C. As shown, the top portion 82 is in the form of an annular diskhaving a central opening 84, a proximal surface 86, and a distal surface88. One or more apertures 90 are formed through the top portion 82 andare configured to receive the proximal ends of the cables 15 shown inFIGS. 1-3. Where multiple apertures 90 are provided, the apertures in anexemplary embodiment are spaced an equal distance apart from each otherabout the circumference of the central opening 84. The proximal surface86 of the top portion 82 can include a snap ring 78 configured to couplethe housing 12 to a seal housing 30 such that the working channel 34 ofthe seal housing 30 is substantially coaxial with the central opening 84formed through the top portion 82. The distal surface 88 of the topportion 82 can include one or more rotation locks formed thereon ortherein. In the illustrated embodiment, the rotation locks are in theform of a pair of L-shaped male tabs 92 extending distally from thedistal surface 88.

The base portion 80 of the housing 12 is shown in more detail in FIGS.5D-5F. Like the top portion 82, the base portion 80 is generally in theform of an annular disk having a central opening 94, a proximal surface96, and a distal surface 98. When assembled, the central opening 94 inthe base portion 80 can be configured to be substantially coaxial withthe central opening 84 in the top portion 82, the working channel 34 ofthe seal housing 30, and a working channel of the cannula 14 such that acontinuous working channel exists through the entire length of theaccess device 10. The proximal surface 96 of the base portion 80 caninclude one or more rotation locks formed thereon or therein. In theillustrated embodiment, the rotation locks are in the form of a pair ofL-shaped female slots 100 configured to receive the male tabs 92 formedon the distal surface 88 of the top portion 82. A person having ordinaryskill in the art will appreciate that the tabs 92 and slots 100 can beswapped such that the top portion 82 includes the female slots and thebase portion 80 includes the male tabs. A variety of other rotationlocking mechanisms known in the art can also be employed to restrictrotation of the top portion 82 and the base portion 80 with respect toeach other. One or more apertures 102 can be formed in the base portion80 that are configured to slidably receive the cables 15 of FIGS. 1-3therethrough, as will be explained in detail below. In addition, one ormore pins 104 can be formed on the distal surface 98 of the base portion80 to assist in mating the base portion 80 to the cannula 14.

The cannula 14 can also have various shapes and configurations. In oneembodiment, as shown in FIGS. 6A and 6B, the cannula 14 includes aflexible and/or stretchable sheath 106 extending distally from anannular flange 108. The annular flange 108 can have one or moreapertures 110 formed therein for receiving the pins 104 formed on thedistal surface 98 of the base portion 80 and for mating the cannula 14to the housing 12. The cannula can further include one or more foldingwalls 112 extending distally from the flange 108. In the illustratedembodiment, four folding walls 112 are shown spaced approximately 90degrees apart about the circumference of the annular flange 108.

In one embodiment, the folding walls 112 include a plurality of segmentsand, in particular, can include at least one long segment and at leastone short segment having a length less than a length of the longsegment. In the illustrated embodiment, each folding wall 112 includesthree long segments E1, E2, E3 and three short segments S1, S2, S3. Asshown, the segments can be defined by living hinges 113 formed in theinterior surface 114 and/or exterior surface 116 of the folding walls112. The living hinges 113 can alternate between being formed in theinterior surface 114 of the folding wall 112 and the exterior surface116. In addition, the long segments can have progressively increasinglengths from the proximal end of the folding walls to the distal endand/or the short segments can each have substantially the same length.For example, in FIG. 6B, all three short segments S1, S2, S3 have thesame length L. The long segments E1, E2, E3, on the other hand, haveprogressively increasing lengths such that the length L3 of thedistal-most segment E3 is greater than the length L2 of the intermediatesegment E2, which is in turn greater than the length L1 of theproximal-most segment E1. Forming the long segments with progressivelyincreasing lengths from the proximal end to the distal end of thefolding walls allows the folding walls to take an angled orientationwhen folded to define a substantially conical opening. For example, FIG.6C shows a folding wall in its unfolded state wherein each of thesegments S1, S2, S3, E1, E2, E3 are substantially aligned parallel to alongitudinal axis A of the cannula. FIG. 6D illustrates the same foldingwall after having been folded at each living hinge. As shown, the foldedwall extends at an angle from the axis A.

The seal housing 30, housing 12, and cannula folding walls 112 can beformed from a variety of materials known in the art, including but notlimited to various polymers, including polycarbonates andpolyetheretherketone (PEEK), metals such as titanium or stainless steel,composites such as carbon-fiber reinforced PEEK, various ceramicmaterials, and/or any combination thereof. These structures can also beformed of various semi-rigid/flexible materials, including polyurethanessuch as Pellethane (available from The Dow Chemical Company of Midland,Mich., USA), thermoplastic elastomers such as Santoprene (available fromExxonMobil Chemical of Houston, Tex., USA), polyisoprene elastomers,medium to high durometer silicone elastomers, and/or any combinationthereof. A person having ordinary skill in the art will recognize thatany other suitable material, such as fabrics, foams, plastics, and/ormetals, can be used to form the structures and devices disclosed hereinand that each of the structures and devices can be made from the samematerials or from different materials or from any combination ofmaterials. The cannula sheath 106 can be formed from a variety ofmaterials known in the art, including for example various plastics,silicone, polyisoprene, other elastomers or rubbers, and/or anycombination thereof. The material or materials chosen for the cannulasheath 106 can have a combination of optimal attributes such asflexibility, strength, durability, breathability, microbial resistance,etc.

As noted above, the access device 10 can also include an actuatorconfigured to move the cannula between the insertion configuration andthe expanded configuration. The actuator can include a variety ofdifferent mechanisms for effecting movement of the cannula.

In one embodiment, as shown for example in FIG. 2, the actuator includesat least one cable 15 extending distally from the housing 12 to thedistal end 22 of the cannula 14, where it is attached thereto. Thecables 15 can be attached to the distal end 22 of the cannula 14 usingany suitable method known in the art, for example by threading thecables 15 through one or more apertures formed in the cannula 14 untilan enlarged head or knot at the distal end of the cable 15 engages anouter surface of the cannula 14 and prevents further threading of thecable therethrough. The proximal end of the cables 15 can extendproximally through the apertures 102 in the base portion 80 of thehousing 12 and into the apertures 90 formed in the top portion 82 of thehousing 12. The cables can be fixedly attached within the top portionapertures 90 and slidably disposed through the base portion apertures102. An annular recess 118 can be formed in the proximal surface 98 ofthe base portion 80 and can be sized to accommodate a length of thecables 15, as shown for example in FIG. 5E.

In use, as shown in FIG. 2, rotation of the housing top portion 82, towhich the cables 15 are fixedly attached, with respect to the housingbase portion 80 is effective to selectively tension the cables 15. Forexample, when the base portion 80 is abutted against and fixed to thetissue wall 16, and the top portion 82 is rotated with respect thereto,the cables 15 are translated proximally through the base portionapertures 102. As the top portion 82 is rotated, the top portionapertures 90 become radially offset from the base portion apertures 102,causing the cables 15 to bend approximately 90 degrees in two places atthe junction between the base portion 80 and the top portion 82 and tobe taken up in and wound around the annular recess 118. The proximaltranslation of the cables 15 pulls the folding walls 112 of the cannula14 into a folded position, which in turn deforms the cannula sheath 106and the surrounding incision outward into a substantially conical shape.The top portion 82 can be rotated until the male tabs 92 formed on thedistal surface 88 thereof engage and lock with the female slots 100formed on the proximal surface 96 of the base portion 80. The lockingengagement between the tabs 92 and the slots 100 prevents rotation ofthe top portion 82 with respect to the base portion 80 in eitherdirection and thus locks the cannula 14 in the expanded, substantiallyconical shape. The cannula 14 can be expanded before, during, or after aseal housing 30 is attached to the housing 12 and, as noted above, theseal housing 30 can optionally be integrally formed with the housing 12.

As illustrated for example in FIG. 1, when the tabs 92 are subsequentlydisengaged from the slots 100, the resilient properties of the tissuewall incision can force the folding walls 112 of the cannula 14 backtowards a substantially cylindrical insertion configuration. This can inturn draw the cables 15 distally through the base portion apertures 102and rotate the top portion 80 until the top portion apertures 90 aresubstantially aligned with the base portion apertures 102 and the cables15 are substantially straight.

In another exemplary embodiment, shown for example in FIGS. 7A-7E, theactuator can include a plurality of biasing elements instead of, or inaddition to, the cables described above. FIG. 7A shows the cannula 14′of an access device 10′ inserted into a tissue wall 16′ such that thehousing 12′ of the access device 10′ rests against an outer surface ofthe tissue wall 16′. As shown, the cannula 14′ is inserted in a firstinsertion configuration in which it has a substantially cylindricalshape. One or more biasing elements 120 can be disposed within the innerlumen of the cannula 14′ and can be biased to expand radially, therebyforcing the cannula 14′ into the expanded, conical configurationdescribed above. In the illustrated embodiment, the biasing elements 120are in the form of coiled springs. One or more retaining elements 122coupled to the biasing elements 120 can also be provided. The retainingelements 122 can be configured to maintain the biasing elements in aradially contracted position (i.e., a reduced diameter configuration).In use, releasing the retaining elements 122 can allow the biasingelements to expand radially against the inner surface 114 of the cannula14′.

An obturator 124 configured for releasing the retaining elements 122 canalso be provided. The obturator 124 can have a variety ofconfigurations, but in the illustrated embodiment it is in the form ofan elongated tubular body 126 with a handle 128 formed on a proximal endthereof. An elongate, diametrical slot 130 and/or a clearance groove 132can be formed in a distal portion of the obturator body 126. Thediametrical slot 130 can extend all the way through the obturator body126, such that the distal portion is separated into two opposed arms134, 136. At least one edge 138 of at least one of the opposed arms 134,136 can be sharpened, serrated, and/or otherwise configured to sever theretaining elements 122 upon application of sufficient force.

In use, the obturator body 126 can be inserted through the workingchannel of the access device 10′. The obturator handle 128 can remainoutside of the access device 10′, acting as a stop against the housing12′ to prevent over-insertion of the obturator 124 and to provide agripping point for a user. When inserted, the opposed arms 134, 136straddle the retaining elements 122 disposed within the cannula 14′,such that the retaining elements are disposed within the diametricalslot 130 in the obturator. Once the access device 10′ has been placedthrough the tissue wall with the cannula 14′ in a substantiallycylindrical insertion configuration and the obturator 124 insertedtherethrough, the obturator 124 can be rotated with respect to theaccess device 10′ such that the sharpened edge 138 of the opposed arm(s)134, 136 severs one or more of the retaining elements 122. After theretaining elements 122 are severed, the biasing elements 120 to whichthey are attached become free to expand radially against the interiorsurface 116 of the cannula 14′, forcing the cannula towards asubstantially conical expanded configuration. As illustrated, thebiasing elements 120 can be substantially aligned with the living hinges113 formed in the folding walls 112 of the cannula 14′ to achievemaximal expansion.

Where multiple biasing elements 120 are provided, they can be sized tohave progressively increasing diameters in their unrestrained statesthat correspond to the progressively increasing lengths of the cannula'sfolding wall segments. In the embodiment of FIG. 7A-7E, three biasingelements 120 are disposed within the cannula 14′. FIG. 7B shows theproximal-most biasing element 120P, FIG. 7C shows the intermediatebiasing element 1201, and FIG. 7D shows the distal-most biasing element120D. The biasing elements 120 in each of these figures is shown fromabove being maintained in a restrained diameter by a retaining element122. The unrestrained diameter of the biasing elements 120 is shown inphantom.

As illustrated, the biasing elements 120P, 1201, and 120D haveprogressively increasing diameters in their unrestrained states suchthat the diameter of the distal-most biasing element 120D is greaterthan the diameter of the intermediate biasing element 1201, which is inturn greater than the diameter of the proximal-most biasing element120P. In their restrained states, each of the biasing elements 120 havesubstantially the same diameter. As shown in FIG. 7E, this progressivesizing of the biasing elements 120 in their unrestrained states,combined with the progressive sizing of the folding wall segments of thecannula 14′, facilitates deformation of the cannula 14′ to asubstantially conical shape.

In some instances it can be desirable to re-wind the biasing elements120 after the retaining elements 122 have been severed, for example whenit is necessary to remove the access device 10′ from the tissue wall. Tothat end, the biasing elements 120 can further include a graspingfeature 140 formed at a terminal end thereof to facilitate re-winding.As shown in FIGS. 7B-7D, the grasping feature 140 can be in the form ofa small loop formed at or near a terminal end of the coiled springbiasing element 120. A surgical grasping tool or other suitable devicecan be inserted through the working channel of the access device 10′ togrip the grasping feature 140 and re-wind the biasing element 120. Theclearance groove 132 formed in the obturator body 126 can be sized toaccommodate the grasping feature 140, as shown for example in FIGS.7B-7D.

In another embodiment, a solid-tipped obturator, e.g., an obturatorwithout a diametrical slot, can be provided that is configured to severthe retaining elements as the obturator is advanced distally into theaccess device. In addition, the retaining elements can include bothhorizontal retaining elements, which can restrain a biasing element fromradial expansion, and vertical retaining elements, which can restrain abiasing element from longitudinal expansion. FIGS. 7F-7H illustrate oneembodiment of such a configuration. In FIG. 7F, a solid-tipped obturator142 is shown advancing distally into a biasing element 120′. The biasingelement 120′ includes a horizontal retaining element 122H and a verticalretaining element 122V. When the obturator 142 is advanced in thedirection of the arrow 144, it can sever the horizontal retainingelement 122H attached to the biasing element 120′. FIG. 7G shows theobturator 142 having been advanced through the biasing element 120′, andhaving severed the horizontal retaining element 122H, such that thebiasing element 120′ is allowed to expand radially in the direction ofarrows 146 and thereby urge a cannula (not shown) towards an expandedconfiguration. The vertical retaining element 122V is not severed by theobturator 142.

When it later becomes desirable to return the cannula to an insertionconfiguration, a cutting tool can be inserted through the workingchannel of the access device to sever the vertical retaining element122V. FIG. 7H illustrates the biasing element 120′ after the verticalretaining element 122V has been severed. As shown, the biasing element120′ is allowed to expand longitudinally in the direction of arrows 148.This longitudinal expansion causes a commensurate radial contraction inthe direction of arrows 150, allowing the cannula (not shown) to returnto a substantially cylindrical insertion configuration.

In another exemplary embodiment, shown for example in FIGS. 8A-8B, theactuator can be in the form of one or more bimodal rings 152. A bimodalring 152 in accordance with this embodiment has a first configuration(shown in FIG. 8A) in which it has a convex interior surface 154 and amaximum diameter D1. The bimodal ring 152 also has a secondconfiguration (shown in FIG. 8B) in which it has a concave interiorsurface 156 and a maximum diameter D2, which is greater than thediameter D1. When an obturator 158 is inserted through a bimodal ring152 in the first configuration, the convex interior surface 154 can beurged radially outward by the obturator 158 until the bimodal ring“snaps” into the second configuration. The one or more bimodal rings 152can be progressively sized such that the radial expansion that occurswhen the rings 152 are transitioned from the first configuration to thesecond configuration is effective to deform a cannula in which the ringsare disposed into a substantially conical shape. In an exemplaryembodiment, the rings are formed from a flexible, semi-resilientmaterial, such as various plastics, polymers, rubbers, and/or metalsknown in the art.

In yet another embodiment of an access device, the actuator can includea plurality of springs disposed circumferentially around the cannula andbiased to apply an inward force to the cannula, biasing the cannula tothe expanded configuration. An obturator can be provided in suchembodiments that is configured such that insertion of the obturator intothe cannula is effective to radially expand the plurality of springs,thereby moving the cannula to an insertion configuration. When theobturator is removed, the springs are allowed to radially contract,moving the cannula to the expanded configuration. FIG. 9A illustrates anaccess device 10″ and an obturator 160 inserted therethrough beingadvanced distally through a tissue wall 16″. A plurality of springs 162are disposed circumferentially around the cannula 14″. The cannula 14″can be similar or identical to the cannulas 14, 14′ described above, andcan thus have one or more folding walls 112′ that include a plurality oflong segments 164 and a plurality of short segments 166. The longsegments 164 can have progressively increasing lengths from the proximalend of the cannula 14″ to the distal end, while the short segments canhave substantially the same lengths. The plurality of springs 162 can besubstantially aligned with the living hinges 113′ formed on the interiorsurface of the cannula 14″, which, together with the living hinges 113′formed on the exterior surface of the cannula 14″, define the pluralityof segments in the folding wall or walls 112′.

As shown in FIG. 9B, when the obturator 160 is removed from the accessdevice 10″, the plurality of springs 162 are allowed to radiallycontract, collapsing the folding walls 112′ slightly at each interiorsurface living hinge. The alignment of the springs 162 with the interiorsurface livings hinges causes the short segments 166 to angle inwardlytowards a longitudinal axis of the cannula 14′, which in turn causes thelong segments 164 to angle outwardly away from the longitudinal axis.The progressively increasing lengths of the long segments 164, incombination with this outward angulation, results in the cannula 14″taking a substantially conical shape, as shown. The housing 12″ of thisembodiment, as well as the housings of all other embodiments discussedherein, can optionally include one or more slots, tabs, and/or apertures168 for receiving tie down sutures 170 or any other suitable device forsecuring the housing 12″ to the tissue wall 16″.

FIG. 10A illustrates another exemplary embodiment of an access device200. The access device generally includes a housing 212 and a cannula214 extending therefrom. The access device 200 can also include one ormore seals, as explained above with respect to FIG. 1. The seals can bedisposed in any portion of the access device 200, including in aseparate seal housing (not shown). The housing 212, cannula 214, andseal housing can have substantially the same features as the housings12, cannulas 14, and seal housings 30 described above. In theillustrated embodiment, the cannula 214 includes a flexible, expandablesheath 217. The cannula 214 also includes a coil spring 219 having aproximal end 221 that is coupled to the housing 212 and a distal end223. The housing 212 can include an aperture configured to receive theproximal end 221 of the spring 219. The distal end 223 of the spring 219can be configured to rotate relative to the housing 212 such that thecoil spring 219 winds or unwinds to adjust a diameter of the cannula214. The coil spring 219 can be shaped such that, when unwound, it has agenerally conical shape and when wound, it has a generally cylindricalshape. For example, the coil spring 219 can have a plurality of coilsextending radially around a longitudinal axis of the cannula 214 and canbe biased to a configuration in which the diameter of each individualcoil increases progressively from the proximal-most coil to thedistal-most coil. When configured in such a way, the coil spring 219 canbe wound to allow the cannula 214 to move to an insertion configurationin which it has a substantially constant outer diameter and can beunwound to stretch the cannula 214 to an expanded configuration in whichthe diameter of the cannula 214 increases from the proximal end of thecannula to the distal end of the cannula. An obturator 225 can also beprovided that has a distal end 227 configured to engage the distal end223 of the coil spring 219 such that rotation of the obturator iseffective to rotate the distal end 223 of the coil spring 219 relativeto the housing 212 and thus to wind or unwind the coil spring 219.

As shown in FIG. 10A, the coil spring 219 can be wound such that thecannula 214 has a substantially constant outer diameter. An obturatorcan be inserted through the access device 210 to maintain the spring 219in a wound state. A diametrical slot 229 formed in the distal end 227 ofthe obturator 225 can receive and engage the distal end 223 of the coilspring 219, which can extend at least partially across a longitudinalaxis of the cannula, as shown for example in FIG. 10B. One or more snapconnections 231 can be included to lock the obturator handle 233 to thehousing 212 such that it cannot rotate with respect thereto. Locking theobturator with respect to the housing 212 can prevent the coil spring219 from unwinding. Once the access device 210 is inserted through thetissue wall 216, one or more sutures or other suitable tie-downmechanisms can be coupled to one or more anchor slots 235 formed in thehousing 212 to secure the access device 210 to the tissue wall 216.

As shown in FIG. 10C, the snap connections 231 can be released to allowthe obturator 225 to rotate with respect to the housing 212. The biasednature of the coil spring 219 can cause it to unwind, thereby rotatingthe obturator 225. A force can be applied by the surgeon to theobturator handle 233 to “brake” or otherwise modulate the rotation speedof the obturator 233 and therefore the unwinding speed of the coilspring 219. One or more sutures 237 can be threaded through the anchorslots 235 to prevent the housing 212 from rotating with respect to thetissue wall 216 due to the force of the unwinding coil spring 219 whenthe snap connections 231 are released. Once the coil spring 219 isunwound, the cannula 214 is deformed to form a substantially conicalopening through the tissue wall 216. The obturator 225 can then bewithdrawn proximally from the access device 210 to allow attachment of aseal housing or to allow insertion of other surgical tools through thedevice 210.

As shown in FIGS. 10C-10D, a zero-closure seal 242, such as a duckbillseal as described above, can be provided in the cannula 214 and/or thehousing 212. A person skilled in the art will appreciate that the seal242 allows the obturator 225 to be withdrawn from the device 210 withoutcompromising the insufflation of the body cavity underlying the tissuewall 216. In other words, the seal 242 can maintain insufflationpressure after the obturator 225 is removed but before a seal housing 30is attached to the housing 212.

The conical opening formed by the access device 210 when the coil spring219 is unwound can advantageously allow surgical instruments insertedthrough the device to be angulated to a much greater degree than in atypical cylindrical cannula device, as depicted in FIG. 10E. The conicalshape also aids in retention of the access device 210, as it can preventunintended proximal translation of the device with respect to the tissuewall 216. In addition, the biased nature of the coil spring 219 canforce the cannula sheath 217 against the tissue wall 216 to increase theintegrity of a seal formed therebetween.

When it is desirable to return the cannula 214 to the insertionconfiguration, such as when a surgical procedure has been completed, theobturator 225 can be used to re-wind the coil spring 219, as shown forexample in FIG. 10F. The obturator 225 can be inserted through thehousing 212 at a slight angle such that the diametrical slot 229 formedin the distal end 227 thereof can engage the distal end 223 of the coilspring 219. Once engaged, the obturator 225 can be rotated with respectto the housing 212 to wind the coil spring 219 and return the cannula214 to the insertion configuration. Again, the sutures 237 can preventthe housing 212 from rotating as the obturator 225 is rotated to windthe spring 219. After the coil spring 219 is sufficiently wound, thesnap connections 231 can be engaged to lock the obturator 225 withrespect to the housing 212 and prevent rotation therebetween. The accessdevice 210 can then be withdrawn proximally from the tissue wall 216.

In use, the devices disclosed herein can enable a user to access asurgical site and to conduct one or more surgical procedures. Althoughvarious methods of using surgical access devices are discussed hereinwith respect to particular embodiments of surgical access devices andtheir related components, a person skilled in the art will recognizethat, to the extent that the features of the various surgical accessdevices disclosed herein are interchangeable between embodiments, manyof the steps of the methods are likewise interchangeable.

Generally, a surgical site can be accessed by inserting a cannula of thesurgical access device through a tissue wall. For example, in oneembodiment an incision can be formed through the abdominal wall of apatient and the cannula can be inserted therethrough in an insertionconfiguration. The cannula can then be manipulated in a variety of waysto take on an expanded configuration and thereby create a conicalopening through the tissue. In one embodiment, the cannula can havefolding walls that can be folded to form the conical shaped opening. Forexample, in the surgical access device 10 of FIGS. 1-2, the housing topportion 82 can be rotated with respect to the housing base portion 80 todraw the cables 15 proximally and/or apply tension to the cables 15 andthereby fold the folding walls 112 of the cannula 14. The cannula canalso be folded using a variety of other techniques, for example byinserting an obturator through the cannula to sever one or moreretaining elements to allow one or more biasing elements to expandradially as shown in FIGS. 7A-7E and/or by removing an obturator fromthe cannula to allow one or more springs to contract radially against anouter surface of the cannula as shown in FIGS. 9A-9B. The conical shapedopening can also be formed by releasing a coil spring disposed withinthe cannula such that the coil spring radially expands and causes thecannula to radially expand as shown in FIGS. 10A-10F. Either before orafter forming the conical opening through tissue, one or more sutures orother tie-down features known in the art can be used to secure thesurgical access device. The seal housing can be attached to the deviceeither prior to or after insertion of the cannula through the tissuewall. Insufflation fluid can be applied to the surgical site via aninsufflation port, as shown for example in FIG. 4. One or moreinstruments can then be inserted through and/or removed from thesurgical access device to perform any number of procedures. When theprocedure is complete, the cannula can be moved to the insertionconfiguration and then removed from the tissue wall.

The devices disclosed herein can be designed to be disposed of after asingle use, or they can be designed to be used multiple times. In eithercase, however, the device can be reconditioned for reuse after at leastone use. Reconditioning can include any combination of the steps ofdisassembly of the device, followed by cleaning or replacement ofparticular pieces, and subsequent reassembly. In particular, the devicecan be disassembled, and any number of the particular pieces or parts ofthe device can be selectively replaced or removed in any combination.Upon cleaning and/or replacement of particular parts, the device can bereassembled for subsequent use either at a reconditioning facility, orby a surgical team immediately prior to a surgical procedure. Thoseskilled in the art will appreciate that reconditioning of a device canutilize a variety of techniques for disassembly, cleaning/replacement,and reassembly. Use of such techniques, and the resulting reconditioneddevice, are all within the scope of the present application.

Preferably, the invention described herein will be processed beforesurgery. First, a new or used instrument is obtained and if necessarycleaned. The instrument can then be sterilized. In one sterilizationtechnique, the instrument is placed in a closed and sealed container,such as a plastic or TYVEK bag. The container and instrument are thenplaced in a field of radiation that can penetrate the container, such asgamma radiation, x-rays, or high-energy electrons. The radiation killsbacteria on the instrument and in the container. The sterilizedinstrument can then be stored in the sterile container. The sealedcontainer keeps the instrument sterile until it is opened in the medicalfacility.

It is preferred that device is sterilized. This can be done by anynumber of ways known to those skilled in the art including beta or gammaradiation, ethylene oxide, steam, and a liquid bath (e.g., cold soak).

One skilled in the art will appreciate further features and advantagesof the invention based on the above-described embodiments. Accordingly,the invention is not to be limited by what has been particularly shownand described, except as indicated by the appended claims. Allpublications and references cited herein are expressly incorporatedherein by reference in their entirety.

1. An adjustable access device, comprising: a housing; an expandablecannula extending distally from the housing, the expandable cannulaincluding a coil spring having a proximal end coupled to the housing anda distal end configured to rotate relative to the housing to adjust adiameter of the cannula such that the coil spring is effective to movethe expandable cannula between an insertion configuration, in which thecannula has a substantially constant outer diameter between a proximalend and a distal end, and an expanded configuration, in which thediameter of the cannula increases from the proximal end of the cannulato the distal end of the cannula.
 2. The device of claim 1, furthercomprising at least one seal element disposed within a working channelextending through the housing and the cannula, the at least one sealelement being configured to form at least one of a seal around aninstrument disposed through the working channel and a seal across theworking channel when no instrument is disposed therethrough.
 3. Thedevice of claim 1, wherein the cannula includes at least one sheathdisposed around the coil spring.
 4. The device of claim 1, wherein thedistal end of the coil spring extends at least partially across alongitudinal axis of the cannula.
 5. The device of claim 1, wherein thecoil spring has a plurality of coils extending radially around alongitudinal axis of the cannula, the spring being biased to an expandedconfiguration in which a distal coil of the spring has a diametergreater than a diameter of a proximal coil of the spring such that thespring defines a conical opening extending therethrough.
 6. The deviceof claim 1, further comprising an obturator having a distal endconfigured to engage the distal end of the coil spring such thatrotation of the obturator is effective to rotate the distal end of thecoil spring relative to the housing.
 7. The device of claim 6, whereinthe distal end of the obturator includes a longitudinally-extending slotformed therein for receiving and engaging the distal end of the coilspring.
 8. The device of claim 6, wherein the obturator includes amating element formed on a proximal portion thereof, the mating elementbeing configured to engage the housing to prevent rotation of theobturator with respect to the housing.
 9. The device of claim 1, whereinthe housing includes one or more suture anchors to facilitate securingthe housing to a tissue.
 10. A method for accessing a surgical site,comprising: inserting a cannula of a surgical access device through atissue wall; releasing a coil spring disposed within the cannula suchthat the coil spring radially expands to cause the cannula to radiallyexpand into a conical configuration thereby forming a conical openingthrough the tissue wall.
 11. The method of claim 10, wherein releasingthe coil spring comprises releasing a distal end of the coil spring suchthat the distal end of the coil spring rotates relative to a proximalend of the coil spring and relative to a housing coupled to the proximalend of the coil spring.
 12. The method of claim 11, wherein the distalend of the coil spring is released from an obturator engaging the coilspring.
 13. The method of claim 10, wherein releasing the coil springincludes detaching an obturator from a housing coupled to a proximal endof the cannula to release a distal end of the coil spring from a distalend of the obturator.
 14. The method of claim 10, further comprisingengaging a distal end of the coil spring and rotating the distal end ofthe coil spring relative to the housing to wind the coil spring andthereby move the cannula to an insertion configuration, in which aninner diameter of the cannula is substantially constant.